A precise knowledge of the pharmacodynamic effect of the K2CG chewing gum on salivary phosphorus is expected to provide information necessary to plan and conduct a subsequent interventional trial with K2CG chewing gum in patients with both Chronic Kidney Disease and ESRD. Specifically, quantification of the amount of salivary phosphorus that binds to 3 formulations of chitosan loaded chewing gum (20 mg, 40 mg and 60 mg) with varying exposure times will inform the optimal duration of exposure relative to gum size. The effect of gum size will be further explored via the use of two different sizes of placebo chewing gum (1.7 g and 2.0 g sizes). Additionally it is a specific aim of this study to assess whether chewing gum in the fasted vs. fed state affects the binding characteristics of chitosan loaded chewing gum.